Loreson, no offense taken by your concerns. Actually, I had the same concerns about this construction with no 2 x's and such, so I PM'd the guy who built his on another forum. He is a very experienced carpenter and cabinet maker and told me of the compression strengths of oak plywood stood on end, as taught to him by others with 30+ years of experience. According to him, plywood on end has the strength of like 11 1x3's nailed together. It was explained to me how 2x4 and 4x4 construction was WAY overbuilt, not to mention very heavy. And honestly, I looked at the construction of my manufactured 72g bowfront stand, and it is basically the same thing.
And yes to the last question, it is drag racer. NHRA Competition Eliminator.
Yup, no need for 2x4's at all. You could make that whole stand out of MDF if you wanted to and it would hold that tank no problem. If you have the skill you can make a strong stand out of just about anything. If you are not used to working with wood or have limited tools, then using 2x4's is sometimes simpler and more bullet proof for the novice.
My next stand is being made out of all Pine 3/4 stock.
As for the Danish oil. - It is easy to repair damage to the stand with an oil finish applied. However, oil finishes are not tolerant of long term or regular water exposure, so swabbing up small spills is important. Once the oil has hardened - you can take paste wax and buff the stand. That will add some protection and add a bit more shine than what the oil will give you.
Now... If you want more durability and want to maintain the ability to repair blemishes in the stand you can top coat it with blond Shellac. Shellac is not immune to water damage but holds up pretty well if you put multiple coats on. Shellac is dissolved in alcohol, so you can take denatured alcohol and rub out a water spot/damaged area and simply re-coat that area.... Many antiques were protected with shellac back in the day and that is what makes repairing them a bit easier.
You can also top coat with an oil based poly -Hard to find if you live in California. Do not try to use a water based poly over the danish oil...It will not coat well and look like crap. Two or three coats of poly offers the best protection against water damage, but is very difficult to repair when compared to Shellac.
Shellac or poly, make sure you wait 5 or more days to let the danish oil completely cure and sand in-between coats.
I digress... PM me with any questions.